Implantable bladder stimulator



Feb. 22, 1966 Filed Sept. 6, 1962 W. E. BRADLEY IMPLANTABLE BLADDERSTIMULATOR 2 Sheets-51u29.tl 1

2 Sheets-Sheet 2 Filed Sept. 6, 1962 @Mone/e I fzcmoogs (APAf/TR 0U TPUT COI/PLING l BATTERY POWER PACK PRESS UR E UPERATED `SWITCH INVENTOR.M//LL mM E BRADLEY ATTORNEYJ United States Patent O1 3,236,240IMPLANTABLE BLADDER STIMULATOR William E. Bradley, Minneapolis, Minn.,assignor to The Regents of The University of Minnesota, Minneapolis,Minn., a corporation of Minnesota Fiied Sept. 6, 1962, Ser. No. 221,7549 Claims. (Cl. 12S-421) This invention relates to a method and means forartificially electrically stimulating the bladder of persons who havelost the ability to voluntarily empty the bladder because of spinal cordor other injury or disease. Prior to the present invention, the use of acatheter has been the only means of emptying the bladder of paraplegicsand others similarly affected.

Urinary sepsis, secondary to neurogenic dysfunction associated withspinal cord trauma, is a well recognized clinical problem. Prolonged useof indwelling catheters in paraplegic patients produces significantbacteriuria, cystitis, vesical calculi, and pyelonephritis. It has beenshown that use of an indwelling catheter for 24 hours results inbacteriuria in 50% of patients and in 98-l00% of patients after fourdays.

With antibiotic therapy and closer attention to bladder rehabilitationduring and after World War II, the mortality rate in paraplegics fromurinary sepsis has declined. However, of approximately 746 veterans withspinal cord injury who died during the period of nine years followingWorld War Il, death was attributed to urinary tract infection in 64%. Inanother series of patients, urinary tract damage was found in 65% ofthose dying from other causes.

Bladder tonus, or the response of bladder smooth muscle to the stretchimposed by filling, has been described as an intrinsic property ofsmooth muscle and not reflex in nature. Changes in this response areshown to follow physical alteration in the bladder tissue. Regular,complete evacuation of the neurogenic bladder with avoidance ofinfection and damage, is therefore an aid in preserving normal tonus andfacilitating rehabilitation of bladder function. Electrical excitabilityof the mammalian bladder has been demonstrated.

It is accordingly the principal object of this invention to provide apractical method and means for artificially electrically stimulating thebladder to permit regular, complete evacuation with the avoidance ofinfection and tissue damage.

It is a further object of this invention to provide an implantableinternal bladder stimulator in the form of a radio frequency receiverwith electrodes attached to the bladder, capable of providing the properstimulation when used in conjunction with an external radio frequencytransmitter.

It is another object of this invention to provide a passive internalbladder stimulator adapted to be implanted subcutaneously withelectrodes attached to the bladder which derives its stimulation powerfrom an external high power radio frequency transmitter.

It is another object of the present invention to provide a batterypowered implantable bladder stimulator adapted to be triggered by a lowpower signal from an external pocket size radio frequency transmitter.

A still further object of this invention is to provide a battery poweredimplantable bladder stimulator adapted to be actuated through a pressureswitch by external pressure applied to the skin over the switch.

Other and further objects of the invention are those inherent andapparent in the apparatus as described, pictured and claimed.

To the accomplishment of the foregoing and related ends, this inventionthen comprises the eatures herein- 3,236,243 Patented Feb. 22, 1966 iceafter fully described and particularly pointed out in the claims, thefollowing description setting forth in detail certain illustrativeembodiments of the invention, these being indicative, however, of but afew of the various Ways in which the principles of the invention may beemployed.

The invention will be described with reference to the drawings in whichcorresponding numerals refer to the same parts and in which:

FIGURE l is a perspective view of an internal stimulator according tothe present invention;

FIGURE 2 is a schematic block circuit diagram of an implantable bladderstimulator deriving its stimulation power from an external high powertransmitter;

FIGURE 3 is a schematic block circuit diagram of an implantable bladderstimulator' deriving its stimulation power from an internal batterypower pack and adapted to be triggered from an external radio frequencytransmitter; and

FIGURE 4 is a schematic black circuit diagram of an implantable bladderstimulator deriving its stimulation power from an internal power packand adapted to be actuated by pressure.

As shown in FIGURE l, the stimulator comprises a receiver, indicatedgenerally at 1t), and a plurality of electrodes 11 for attachment to thebladder. The electrodes 1i are connected to the receiver by electricalconductors 12. The receiver is encased in a protective plastic mass 13preferably composed of a synthetic resinous material. The conductors aresimilarly encased in a protective sheath 14.

Referring to FIGURE 2 of the drawings, the bladder stimulator receiverunit includes a tuned tank circuit composed of an inductor and acapacitor in a parallel connected resonant circuit. Since such a circuithas the ability to store energy for a short period of time, its acts asa reservoir or tank. The inductor of the tank circuit acts as anantenna. Pulses of radio frequency energy from an external high powertransmitter of conventional design are transmitted through a layer ofbody tissue to the receiver where they are rectified through arectifier, into a unidirectional pulsating current. The radio frequencycurrent is filtered out and the lower frequency pulse envelope signal isapplied to the bladder through bladder electrodes 11 attached to thebladder wall, through an output coupling capacitor which blocks thedirect current component of the signal. The bladder electrodes l1 aremetallic terminals attached directly to the exterior wall of thebladder.

The receiver components are encased or embedded in a sterilizable,inert, non-irritating and non-toxic protective and insulating mass 12,preferably of synthetic resinous material, with only the conductors 12leading to the bladder electrodes 11 extending therefrom. Thesec-onductors are insulated by passing them through tubes 14, preferablyof similar synthetic resinous protective and insulating material, orcoated with a similar substance. Substances such as silicone rubber,silastic resins, tetrauoroethylene polymers, vinyl chloride and thelike, are suitable materials for these purposes. Pure natural rubber mayalso be used.

The bladder electrodes may be formed from any inert non-toxic andnon-irritating electrically conductive metal. Surgicail grade stainlesssteel is a preferred material. However, other metals such as tantalum,gold, silver, platinum and alloys of these metals may also be used.According to one form the electrodes are circular discs of the order ofabout 0.5 to 1.5 centimeters in diameter and protected on one side withan insulating material. The electrodes may be solid or perforated orformed from metallic mesh. The electrodes are attached with silk suturesor the like sewn through the outermost layer of the bladder wall withthe exposed surface in direct contact with the wall. Two to four leadsor more may be connected from the receiver to the bladder depending uponthe size of the bladder.

The reiver-stimulator is implanted under the skin of the patient withthe electrodes attached directly to the bladder wall. The transmitterwhich accompanies the receiver generates pulses of radio frequencyenergy of the sa-me frequency of the tuned tank circuit modulated to theproper shape and pulse recurrence frequency to give the correct bladderstimulation. This is of the order of about one-half to two megacycles,and desirably about one megacycle. The transmitted radio frequencyenergy is applied to the patient by means of a small loop antenna at theend of a cable extending from the radio frequency generator. This loopis held next to the skin directly over the implanted receiver. Thetransmitted signal stimulates the bladder through the bladder electrodesand causes the badder to empty.

Although the bladder has been found to be responsive to wide variationsin applied signal the components of the stimulator are desirablyselected to apply a biphasic signal of amplitude of aboue 1 to 50 voltsdepending upon the size of the electrodes, the voltage varying inverselywith the contact area of the electrodes. The pulse recurrence frequencymay be up to about 20 times the pulse duration and may be, for example,of the order of about 20 to 2000 cycles per second. In one typicalinstance 6 electrodes of l centimeter diameter were attached to abladder and the applied signal was of the order of about volt, 2millisecond pulses at the rate o-f about 50 to 100 per second.

Referring to FIGURE 3 there is shown a self-powered receiver-stimulator,indicated generally at 10A, which contains its own battery power supply.This receiverstimulator includes a tuned tank :circuit whose inductorVsimilarly acts as an antenna. The pulses of radio frequency energy froma llow power transmitter are transmitted to a radio frequency operatedswitch which controls the battery po-wer pack to energize amultivibrator. The output of the multivibrator is applied to the bladderthrough an output coupling capacitor to block the ow of direct currentwhile permitting pulsating current to pass. The stimulation is appliedthrough the bladder electrodes 11 attached directly to the bladder wall.

This type of receiver-stimulator is likewise encased in a resinousprotective and insulating material 13 and implanted directly in the bodyof the patient under the skin. It has the advantage of permitting theuse o-f a smaller more portable transmitter of pulses of radio frequencyenergy. Along with this is the disadvantage of a limited life, dependentupon the life of the battery power pack. However, the greater mobilityof the patient permitted by the self-powered unit will in most casesoutweigh this disadvantage.

It has been found that eifective and complete emptying of the bladderwith no residual urine may be accomplished through use o-f thereceiver-stimulator according to the present invention. Emptying istime-cycled and the bladder is emptied rat regular intervals. Forexample, a timer may be used to trigger the transmitter every four hoursfor a period of three minutes. lt will be understood, of course, thatthe length and frequency of stimulation may vary ywidely dependent uponthe fluid intake, the condition of the patient, and other variables.

The implanted stimulator may be used over an extended period of timewith minimal tissue reaction in the region of the electrodes and onlyslight thickening of the subcutaneous tissues around the site ofimplantation of the receiver. Meanwhile, infection and subsequentbladder tissue changes resulting from the use of urethral catheters isavoided and bladder tonus is maintained, preserving an intact organ andsphincters. Instead of utilizing radio d, frequency signals asdescribed, ultrasonic vibrations may be used in a similar manner.

In FIGURE 4 there is shown a modified form of stimulator, indicatedgenerally at 10B, which also contains its own battery power supply. Thecircuit of this stimulator includes a pressure operated switch which maybe actuated by finger pressure exerted on the overlying skin. Thepressure switch controls the battery power pack to energize amultivibrator. The output of the multivibrator is applied to the bladderthrough an output coupling capacitor and the stimulation is applied tothe bladder as previously described. By means of this form of stimulatorthe patient has greater freedom and direct control over evacuation ofhis bladder. This unit is insulated and embedded in protective materialin the same manner as the other forms of stimulator and is implanted sothat the pressure switch may be easily actuated by finger pressure onthe skin overlying the unit.

lt is apparent that many modifications and variations of this inventionas hereinbefore set forth may be made without departing from the spiritand scope thereof. The specific embodiments described are given by wayof example only and the invention is limited only by the terms of theappended claims.

I claim:

1. A volitional stimulator for the stimulation of a distended bladder tocause the emptying thereof intermittently at widely spaced timeintervals dictated by liquid intake into the bladder, said stimulatorincluding (A) means for producing controllable intermittent electricalstimuli having an amplitude of about 1 to 50 volts and a pulserecurrence frequency of the order of about 20 to 2000 cycles per second,said frequency being up to about 20 times the pulse duration,

(B) at least two separate electrode means for direct attachment to thebladder wall at variable relatively widely spaced distances,

(C) iiexible electrical conductor means connecting said electrode meansto said means for producing electrical stimuli,

(D) means for actuating said means for producing electrical stimuli toturn said means on to apply a pulsing electrical stimulus to the bladderwall through said electrode means,

(E) means for manually controlling said actuating means for applyingsaid stimulus for a short time interval sufficient to substantiallyempty said bladder intermittently at said widely spaced time intervalsdictated by liquid intake into the bladder,

(F) said means for producing electrical stimuli and said conductor meansbeing encased in an inert nontoxic and non-irritant protective materialin a relatively flat wafer-like envelope and elongated flexible sheaths,respectively, for implantation within the body.

2. A stimulator according to claim 1 further characterized in that saidmeans for producing electrical stimuli is a radio frequency receiver.

3. A volitional receiver-stimulator for the stimulation of a distendedbladder to cause emptying thereof intermittently at widely spaced timeintervals dictated by liquid intake into the bladder, said stimulatorincluding (A) a radio frequency receiver,

(B) at least two separate electrode means for direct attachment to thebladder wall at variable relatively widely spaced distances,

(C) exible electrical conductor means connecting said receiver andelectrode means,

(D) means within the receiver for applying a pulsing electrical stimulusto the bladder through said electrode means,

(E) means for actuating said stimulus applying means to turn said meanson for short time intervals sufcient to substantially empty said bladderat said intermittent widely spaced time intervals dictated by liquidintake into said bladder,

(F) said receiver and conductor means being encased in an inertnon-toxic and non-irritant protective material in a relatively atwafer-like envelope and elongated sheaths, respectively, forimplantation Within the body.

4. A receiver-stimulator according to claim 3 further characterized inthat said receiver includes a radio frequency tuned tank circuit, theinductor of said tank circuit being an antenna for an external radiofrequency signal.

S. A receiver-stimulator according to claim 3 further characterized inthat said receiver includes an output coupling capacitor to block theflow of direct current to said electrodes.

6. A receiver-stimulator according to claim 5 further characterized inthat said receiver includes means for adapting said receiver to bepowered by an external high power radio frequency generator and includesa rectifier for imparting unidirectional ow to the electrical stimulusto said electrodes and a filter to block the ow of radio frequencycurrent.

7. A volitional receiver-stimulator for the stimulation of a distendedbladder to cause emptying thereof intermittently at widely spaced timeintervals dictated by liquid intake into said bladder, said stimulatorincluding (A) a radio frequency receiver,

(B) at least two separate electrode means for direct attachment to thebladder walls at variable relatively widely spaced distances,

(C) flexible electrical conductor means connecting said receiver andelectrode means,

(D) means within said receiver for altering an externally transmittedradio frequency signal and applying a pulsing electrical stimulus to thebladder wall through said electrode means,

(E) means for applying said pulsing electrical stimulus for short timeintervals suicient to substantially empty said bladder at Widely spacedtime intervals dictated by liquid intake into said bladder,

(F) said receiver and conductor means being encased in an inertnon-toxic and non-irritant protective material in a relatively atwafer-like envelope and elongated eXible sheaths, respectively, forimplanting Within the body.

8. A volitional receiver-stimulator for the stimulation of a distendedbladder to cause emptying thereof intermittently at widely spaced timeintervals dictated by liquid intake into said bladder, said stimulatorincluding (A) a radio frequency receiver,

(B) at least two separate electrode means for direct attachment to thebladder Walls at variable relatively widely spaced distances,

(C) tleXible electrical conductor means connecting said receiver andelectrode means,

(D) means within said receiver for altering an externally transmittedradio frequency signal and applying a pulsing electrical stimulus to thebladder wall through said electrode means including:

(1) a tuned tank circuit, the inductor which serves as an antenna for anexternally generated high power radio frequency signal,

(2) a rectifier for imparting unidirectional flow t0 the electricalstimulus to said electrode means,

(3) a filter to block the flow of radio frequency current, and

(4) an output coupling capacitor to block the tlow of direct current tosaid electrode means,

(E) means for applying said pulsing electrical stimulus for short timeintervals sufficient to substantially empty said bladder at widelyspaced time intervals dictated by liquid intake to said bladder,

(F) said receiver and conductor means being encased in an inertnon-toxic and non-irritant protective material in a relatively llatWafer-like envelope and elongated flexible sheaths, respectively, forimplanting Within the body.

9. A volitional method for artificially causing a distended bladder tobe emptied intermittently at widely spaced time intervals dictated byliquid intake into said bladder, which method comprises the steps of (A)mplanting a means for producing electrical stimuli within the body,

(B) connecting said means directly to the bladder Wall at at least tworelatively widely spaced contact areas on opposite sides thereof,

(C) actuating said electrical stimulus producing means implanted withinthe body from externally of the body for short time intervals suicientto substantially empty said bladder intermittently at relatively widelyspaced time intervals dictated by liquid intake into said bladder,

(D) thereby applying pulsing electrical stimuli directly to the bladderwall for said short time intervals at said relatively widely spaced timeintervals to contract the bladder Wall and empty the contents thereof,

(E) said stimuli having an amplitude of about 1 to 50 volts and a pulserecurrence frequency of the order of about 20 to 2000 cycles per second,said frequency being up to about 20 times the pulse duration.

References Cited by the Examiner UNITED STATES PATENTS 623,022 4/1899Johnson 12S-407 1,056,336 3/1913 Hurdrnan 128-407 3,050,695 8/1962 DuVall 12S-421 X 3,057,344- 10/ 1962 Abella 12S-2 3,057,356 10/ 1962Greatbatch 12S- 422 OTHER REFERENCES Schamaun, pp. 640-650 of Surgery,October 1963. Kantrowitz, pp. 595-597 of JAMA, Feb. 22, 1964.

RICHARD A. GAUDET, Primary Examiner. JORDAN FRANKLIN, Examiner.

1. A VOLITIONAL STIMULATOR FOR THE STIMULATION OF A DISTENDED BLADDER TOCAUSE THE EMPTYING THEREOF INTERMITTENTLY AT WIDELY SPACED LINEINTERVALS DICTATED BY LIQUID INTAKE INTO THE BLADDER, SAID STIMULATORINCLUDING (A) MEANS FOR PRODUCING CONTROLLABLE INTERMITTENT ELECTRICALSTIMULI HAVING AN AMPLITUDE OF ABOUT 1 TO 50 VOLTS AND A PULSERECURRENCE FREQUENCY OF THE ORDER OF ABOUT 20 TO 2000 CYCLES PER SECOND,SAID FREQUENCY BEING UP TO ABOUT 20 TIMES THE PULSE DURATION, (B) ATLEAST TWO SEPARATE ELECTRODE MEANS FOR DIRECT ATTACHMENT OT THE BLADDERWALL AT VARIABLE RELATIVELY WIDELY SPACED DISTANCES, (C) FLEXIBLEELECTRICAL CONDUCTOR MEANS CONNECTING SAID ELECTRODE MEANS TO SAID MEANSFOR PRODUCING ELECTRICAL STIMULI, (D) MEANS FOR ACTUATING SAID MEANS FORPRODUCING FOR ELECTRICAL STIMULI TO TURN SAID MEANS "ON" TO APPLY APULSING ELECTRICAL STIMULUS TO THE BLADDER WALL THROUGH SAID ELECTRODEMEANS, (E) MEANS FOR MANUALLY CONTROLLING SAID ACTUATING MEANS FORAPPLYING SAID STIMULUS FOR A SHORT TIME INTERVAL SUFFICIENT TOSUBSTANTIALLY EMPTY SAID BLADDER INTERMITTENTLY AT SAID WIDELY SPACEDTIME INTERVALS DICATED BY LIQUID INTAKE INTO THE BLADDER, (F) SAID MEANSFOR PRODUCING ELECTRICAL STIMULI AND SAID CONDUCTOR MEANS BEING ENCASEDIN AN INERT NONTOXIC AND NON-IRRITANT PROTECTIVE MATERIAL IN ARELATIVELY FLAT WAFER-LIKE ENVELOPE AND ELONGATED FLEXIBLE SHEATHS,RESPECTIVELY, FOR IMPLANTATION WITH THE BODY.